'use strict'

const http = require('http')
const fs = require('fs')

function parseBodyHeaders(data) {
    let headers = {}
    let dsplit = data.split('\r\n').filter(p => p.length > 0)

    let ind
    let k
    for (let d of dsplit) {
        ind = d.indexOf(':')

        if (ind <= 0) continue

        k = d.substring(0, ind).toLowerCase()

        headers[k] = d.substring(ind + 1).trim()

    }

    let cpd = headers['content-disposition']

    //按照; 分割成数组，第一个元素form-data去掉
    let clist = cpd.split('; ').slice(1)

    let name, filename

    for (let a of clist) {
        ind = a.indexOf('filename="')
        if (ind >= 0) {
            filename = a.substring(ind + 10, a.length - 1)
        } else {
            name = a.substring(6, a.length - 1)
        }
    }

    return {
        headers,
        name,
        filename
    }

}

/**
 * 
 * @param {Buffer} bodyData 原始的Body数据
 * @param {Object} reqHeaders reuqest.headers
 */

function parseBody(bodyData, reqHeaders) {

    //content-type: multipart/form-data; boundary=-----34294329
    let ctype = reqHeaders['content-type']

    //拿到分界线boundary
    let bdy = ctype.substring(ctype.indexOf('=') + 1)

    //数据中用于分割文件的分界线
    //let bdy = `--${bdy}\r\n`

    let crlf_bdy = `\r\n--${bdy}`

    //从偏移bdy的长度开始查找下一个分界线的位置
    let data_end_index = bodyData.indexOf(crlf_bdy, crlf_bdy.length)

    //body消息数据中header部分的最后索引
    let header_end_index = bodyData.indexOf('\r\n\r\n', crlf_bdy.length)

    let header_data = bodyData.toString('utf8',
        crlf_bdy.length,
        header_end_index);

    //解析body数据中的消息头
    let hd = parseBodyHeaders(header_data)

    let fileinfo = {
        start: header_end_index + 4,
        end: data_end_index,
    }

    fileinfo.length = fileinfo.end - fileinfo.start

    return {
        name: hd.name,
        filename: hd.filename,
        headers: hd.headers,
        start: fileinfo.start,
        end: fileinfo.end,
        length: fileinfo.length
    }

}

let routerTable = {

    GET: {
        '/upload': async (request, response) => {
            let stm = fs.createReadStream('./upload.html')
            stm.pipe(response)
            stm.on('end', () => {
                response.end()
            })
        }
    },

    POST: {
        '/upload': async (request, response) => {

            console.log(request.headers['content-type'])

            let bufferList = []
            let totalLength = 0

            request.on('data', chunk => {
                totalLength += chunk.length
                bufferList.push(chunk)
            })

            let bodyData = null

            request.on('end', () => {
                bodyData = Buffer.concat(bufferList, totalLength)
                bufferList = []

                //解析Body数据
                let body = parseBody(bodyData, request.headers)
                console.log(body)

                response.setHeader('content-type',
                    'text/plain; charset=utf-8')

                response.end(bodyData)
            })

        }
    }

}

let serv = http.createServer()

serv.on('request', (request, response) => {
    let rm = routerTable[request.method]
    //! 解决带查询字符串问题
    //? 根据?切割字符串
    let usplit=request.url.split('?');
    let pathname=usplit[0];
    //! 问号后面没有东西，usplit[1]为undefined返回空字符
    let querystring=usplit[1] || ''

                //? 不带查询字符串的 
    // if (!rm || !rm[request.url]) {
    //     response.statusCode = 404
    //     response.end('page not found')
    //     return
    // }
    if (!rm || !rm[pathname]) {
        response.statusCode = 404
        response.end('page not found')
        return
    }

    rm[pathname](request, response)
})

serv.listen(3456)

